I have a decision in my favour for a substantial (4-digit) amount of compensation due from Wizz Air UK from their ADR provider, AviationADR. The case relates to EU261 compensation.

The decision is now 2 months old and Wizz Air have not paid. Frustratingly, AviationADR have ceased to respond to (polite and literate) requests for update or information, and it's unclear to me whether there is any more I or they can do by this route.

Is there any mileage in attempting to continue with the ADR route or should I proceed to MCOL? In the past I have experienced, with utility companies, that failure to implement the ADR provider's decision is in itself grounds for a further case, with another £500 in costs for the other party, but this is a different world.

If the answer is MCOL, I'd be grateful for any tips/suggestions/wording.